1. Field of the Invention
The present invention is in the field of wind driven electricity generation.
2. Related Art
Wind as an alternate motive force for generating electricity has long provided an attractive alternative to conventional power generation techniques. The art has been limited by at least two technical difficulties. One is the inconsistency of the wind. Stated alternatively, there is a need in the art for extending the ability of wind driven electricity generation equipment to generate electricity beyond the time when the wind has dropped below velocities sufficient to turn generators. A corollary to this problem is overcoming the frictional resistance to supporting equipment that is large and massive enough to drive larger generating turbines.
Both of the long standing needs have a common denominator; that is the increased friction resistance inherent in using larger equipment capable of driving larger generators and also inherent with incorporating fly wheels for extended generation times. There is a need in the art for a wind driven electricity generating turbine having reduced friction support for its moving parts.
Separately, there is a need for a wind driven electricity generator that is not so structurally high, obtrusive and having such long blades that it interferes with bird life. Present windmills have long arms stationed atop towers that are tall enough to encroach upon the flight paths of birds and consequentially kill a number of them.
Vertical axle wind power generators have always been limited in their size (diameter) due to the forces of gravity.
Vertical axle generators are typically mounted on bearings which are required to bear the total weight of the device. The larger the device, the greater its weight and thus, the greater the bearing load.
Gravity also causes structural sag away from the axle. Therefore, heavier construction methods are required to maintain rigidity as diameters increase, thereby increasing weight loads on the bearing. These factors have limited the size (diameter) of vertical axle wind power generators and have therefore, limited the potential power output of these devices.
Performance is also affected by how a fluid medium such as air is vented, exhausted or outlet from a machine designed to extract energy from the flow of the fluid (wind). Qualitatively stated, the process of extracting energy from an input fluid velocity reduces that velocity. The presence of slow or still fluid at the outlet of the machine impedes the intake of further fluid by the machine, having a braking effect that decreases performance. For some configurations such as turbines, this effect is quantitatively understood as Betz's law. Some prior art devices have used scoops or funnels to advantageously direct fluid intake towards a rotor or other moving apparatus to extract energy from the fluid flow, see for example, U.S. Pat. No. 6,465,899 to Roberts, or U.S. Pat. No. 4,350,900 to Baughman, or U.S. Pat. No. 5,852,331 to Giorgini. Each of these devices suffers from a restricted and inadequate provision for the outlet or venting of the fluid medium (air) away from the energy extraction component (a rotor). There is a need in the art for a device for extracting energy from a fluid flow having intake guide surfaces that also has improved provisions for fluid outlet.
There is a continuing need in the electricity generating art for increasing efficiency, durability, increasing the amount of power generated from a given wind velocity and increasing economy such that electricity may be generated at a reduced cost.